👶 Pregnancy Term Calculator
Determine your pregnancy term classification based on the ACOG definitions. Enter your last menstrual period (LMP) or estimated due date (EDD) to see whether your pregnancy is preterm, early term, full term, late term, or post-term , with a visual term scale and milestone timeline.
What Is a Pregnancy Term Calculator?
A pregnancy term calculator determines which term category a pregnancy falls into based on gestational age. In 2013, the American College of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM) redefined the term categories to better reflect neonatal outcomes and guide clinical decision-making.
The updated ACOG definitions are:
- Preterm , Before 37 weeks 0 days (subdivided into extremely, very, moderate, and late preterm).
- Early Term , 37 weeks 0 days through 38 weeks 6 days.
- Full Term , 39 weeks 0 days through 40 weeks 6 days.
- Late Term , 41 weeks 0 days through 41 weeks 6 days.
- Post Term , 42 weeks 0 days and beyond.
This change was significant because research showed that babies born at 37–38 weeks (previously called "term") had higher rates of respiratory problems, NICU admission, and feeding difficulties compared to those born at 39–40 weeks. The updated classification helps clinicians avoid non-medically indicated early deliveries before 39 weeks.
How Is Term Calculated?
Term is determined from gestational age, which is calculated from the first day of your last menstrual period (LMP) using Naegele's rule:
EDD = LMP + 280 days
where 280 days = 40 weeks from the first day of the last menstrual period
If you know your estimated due date (EDD) instead, the calculator reverses the process: LMP = EDD − 280 days. Gestational age is then calculated from that derived LMP.
For example, if you are 38 weeks and 4 days pregnant, you are in the Early Term category (37–38 weeks). If you are 39 weeks and 2 days, you are Full Term.
Why the Term Classification Matters
The term classification has real clinical implications:
- Preterm birth (before 37 weeks) is the leading cause of neonatal morbidity and mortality worldwide.
- Early term (37–38 weeks) carries slightly elevated risks compared to full term , including respiratory issues and longer hospital stays.
- Full term (39–40 weeks) is the optimal delivery window for neonatal outcomes.
- Late term (41 weeks) and post term (42+ weeks) carry increased risks of stillbirth, meconium aspiration, and macrosomia , closer monitoring and possible induction are typically recommended.
Only about 4% of babies are born on their exact due date; most arrive within a two-week window around it.
Why Use This Calculator?
- ACOG 2013 compliant: Uses the current standard term definitions used by obstetricians.
- Visual term scale: See exactly where your pregnancy falls on the full term spectrum.
- Progress bar: Track your pregnancy journey from 0 to 42 weeks.
- Milestone timeline: View key pregnancy milestones and which ones you've passed.
- Free & private: No registration, no data storage , all calculations are done in your browser.
❓ Pregnancy Term Calculator FAQ
What is the difference between "term" and "full term"?
Term is the broad category covering 37–42 weeks. Full term specifically refers to the optimal window of 39–40 weeks under the 2013 ACOG definitions. Babies born at 37–38 weeks are "early term," not "full term."
What are the 2013 ACOG term definitions?
Preterm: < 37 weeks. Early Term: 37–38 weeks. Full Term: 39–40 weeks. Late Term: 41 weeks. Post Term: 42+ weeks.
How is gestational age calculated?
Gestational age is calculated from the first day of your last menstrual period (LMP) using Naegele's rule: EDD = LMP + 280 days (40 weeks).
Why was the term classification changed in 2013?
The 2013 update was based on research showing that babies born at 37–38 weeks (previously called "term") had higher rates of respiratory problems and NICU admissions compared to those born at 39–40 weeks. The new classification helps clinicians avoid non-medically indicated early deliveries.
What does "early term" mean?
Early term refers to 37 weeks 0 days through 38 weeks 6 days. While these babies are generally healthy, they have slightly elevated risks compared to full-term babies, including respiratory issues and feeding difficulties.
What is "late term"?
Late term is 41 weeks 0 days through 41 weeks 6 days. At this stage, closer monitoring is recommended because the risk of complications (like stillbirth) begins to increase.
What is "post term"?
Post term is 42 weeks 0 days and beyond. Post-term pregnancies carry increased risks of stillbirth, meconium aspiration, and macrosomia (large baby). Induction is often recommended.
How accurate is this calculator?
This calculator uses Naegele's rule and the 2013 ACOG term definitions. However, every pregnancy is unique. An early ultrasound (before 14 weeks) is the most accurate way to date a pregnancy. Always consult your healthcare provider for personalized medical advice.
Can I use this calculator for IVF pregnancy?
IVF pregnancies are dated differently , from the embryo transfer date, not the LMP. Your fertility clinic will provide a specific due date. This calculator is best for natural pregnancies.
Is this calculator free?
Yes, this calculator is completely free to use. No registration or personal data storage is required.